Many force and pressure sensors utilize a strain gauge or Wheatstone bridge circuit. The resistive elements in the bridge change resistance in response to changes in sensed condition, such as in pressure or acceleration, or mechanical strain, which in turn cause the electrical output (e.g., voltage or current) to change corresponding to a change in the sensed condition.
Typical bridge sensors have a differential output signal (Vo+ and Vo−). Ideally, the unloaded bridge output is zero (Vo+ and Vo− are identical). However, inexact resistive values result in a difference between Vo+ and Vo−. This bridge offset voltage can be substantial and vary between sensors causing decreased system accuracy.
Different designs and approaches have been developed to improve the sensitivity of bridge sensors by calibrating them more accurately. Some approaches include providing both offset correction and gain control of the sensor signals. Some designs attempt to address the wide range of sensor data by having on board microprocessor to achieve programmable compensation and calibration. However, as the deployment of small portable devices such as smartphone gets ever broader and the user demand for having more functions and features (thus more sensors) on small portable devices keeps increasing, the need in the art for a solution for highly integrated and versatile sensor conditioner or interface design both in terms of footprint and functionality remains.